1. Field of the Invention
The present invention relates to airbag inflators and more particularly to airbag inflators designed for use on the passenger side of a vehicle behind an instrument panel rather than on the driver's side, which inflators are commonly mounted on the steering wheel. The present invention also relates to pyrotechnic type airbag inflators wherein gas generating pyrotechnic materials are utilized to provide a source of gas for rapid inflation of an associated airbag.
2. Background of the Prior Art
In prior art passenger side airbag inflators of the pyrotechnic type which have worked well, a relatively expensive type igniter is utilized to ignite a stack of washer-like wafers comprising a solid form of gas generant material such as sodium azide. These prior art igniters include an elongated, perforated metal tube wrapped with an adhesive backed metal foil such as a thin aluminum foil and inserted into a central passage of the stack of gas generant wafers.
The igniter tube is filled with granular ignition material and a rapid deflagration cord (RDC) having an adapter cup crimped onto one end and closed with a screen for containing the ignition granules. An exposed length of RDC and a stand off distance are critical features that require close inspection and contribute to the relatively high cost of these igniters. Moreover, prior art igniter tubes provide reduced heat transfer, and tend to confine the granules that distribute hot gas and prevent hot granules from easily spreading throughout the airbag inflator to help ignite the gas generant wafers.